Structural members such as steel columns, beams, girders, plates, and the like are commonly sheathed, wrapped, or otherwise enclosed by layers of insulation for protection. It is conventional to secure the insulation in place by the means of impaling clips of one form or another. U.S. Pat. No. 2,100,624 illustrates on example of such a clip, and its use to attach a layer of fireproofing material around a beam. In that case, only one end of a sheet metal clip is used to penetrate the layer, as the opposite end is used to clamp the clip over a flange of the member. Additional clips would have to be used to impale insulation at a different location on the member. A further disadvantage is that the sheet metal form of the clip requires considerable metal. Still another example is shown in U.S. Pat. No. 2,370,052, wherein asbestos fibers are held in place by a double-pronged sheet metal clip, the center portion of which is welded to an angle beam.
Recently, it has been discovered that a layer or layers of mineral wool felt, when held adjacent to structural members by clips, provide fire resistance sufficient to provide a fire rated structural member. This is disclosed and claimed in United States application Ser. No. 103,231 filed on Dec. 31, 1970, commonly owned with the instant application. Only one end of each clip is disclosed therein as being capable of impaling the felt.